THE FLOW OF ENERGY AND
THE CYCLING OF MATTER
CAN BE TRACED AND
INTERPRETED IN
ECOSYSTMES
KEY CONCEPTS
¢  Interactions
¢  Producers,
¢  Nutrient
and interdependencies
consumers, and decomposers
cycles and energy flow
¢  Environmental
impacts
I WONDER…
¢  What
would you say to getting rid of the biting
insects that attack you each spring and summer?
YOU WOULD PROBABLY SAY YES!
¢ But
studies of ecosystems
suggest that there is no easy
way of eliminating certain
species without harming the
environment.
¢ It
might seem great at first, but
you would soon notice some
important changes.
INSECTS ARE A MAIN FOOD SOURCE:
¢ For
some birds and fish. And what
about the animals that eat the birds
and fish?
¢ Insects
pollinate many flowers, and
without them, many plants would
not produce fruits and seeds. The
animals that eat the fruits and
seeds would suffer.
¢  And,
some insects also have an important role in
breaking down dead and decaying organisms.
INTERACTIONS &
INTERDEPENDENCE
¢ Elements
in an ecosystem are
interdependent. It’s important to
understand these relationships to
see how an ecosystem works.
¢ Interdependence:
a relationship
in which organisms are mutually
dependent on one another.
ECOSYSTEMS HAVE INTERACTIONS AMONG
PRODUCERS, CONSUMERS, AND DECOMPOSERS
¢ By
the time you are in grade 7, your
body mass has probably increased
10 times since you were a baby.
Your body has gone through many
changes.
¢ In
fact, between conception and
birth, the number of cells in your
bodies has increased from 1 to
about 10 trillion.
YOUR BODY…
¢ Has
needed to “fuel” all these
changes.
¢ The
energy and matter than
your body needed came from
food.
¢ Your
body broke down the food
into a form it could use.
CHOOSING THE RIGHT FOOD IS
IMPORTANT…
¢  Because
no one food can supply your body with
everything it needs.
¢  Animals have to choose their food carefully too.
That’s why a shark doesn’t generally “eat”
humans. Our body mass does not supply them
with them with what they need to live.
INTERESTING FACT…
¢ For
a long time scientists thought
hyenas were only scavengers. That’s
because people saw hyenas
scavenging during the day.
¢ Scientists
have since learned that
hyenas do hunt, but only at night.
They are skilful and cunning
hunters.
YOU AND OTHER ANIMALS ARE FOOD
CONSUMERS
¢ In
science, a consumer is any
organism that has to seek out and
eat, or consume, other living things
for food. (In the common language
meaning of the word, people are
also called consumers because they
“consume” goods and services.)
¢ ALL
animals are food consumers.
CARNIVORES
¢  Scientists
find it helpful to classify consumers
based on the kinds of food they eat.
¢  Animals, like cats, hyenas, seals, and praying
mantises, which consume mainly animal food,
are called carnivores.
HERBIVORES
¢  Animals
like moose, elephants, and
grasshoppers, which consume mainly plants,
and plant-like living things, are called
herbivores.
OMNIVORES
¢  Animals
like humans, bears, and
raccoons, which consume other animals as
well as plants, are called omnivores.
FOOD CONSUMERS DEPEND ON FOOD
PRODUCERS.
¢ Plants
and plant-like living things
play an important role in nearly all
ecosystems on Earth.
¢ Plants
can do something that you
and other food consumers cannot.
¢ What??!!
PRODUCERS
¢ Green
plants can nourish
themselves. You cannot!!
¢ Animals
must find food to eat to get
the matter and energy they need to
survive.
¢ Organisms
that can nourish
themselves are known as
producers. They can make their
own food to supply the matter and
energy they need to survive.
THE PROCESS OF
PHOTOSYNTHESIS
¢  Plants
need 2 raw materials to make their food.
Raw materials are materials in their natural
state. They have not been manufactured.
WATER & CARBON DIOXIDE
¢ Are
the 2 raw materials that
plants need to make their own
food.
¢ Water comes from the soil, and
carbon dioxide comes from the
air.
¢ Plants also need energy to make
their food, and this energy comes
from the sun.
PLANTS ABSORB THE SUN’S ENERGY
THROUGH THEIR LEAVES.
¢  Inside
the leaves, this energy is used to
rearrange the particles that make up
water and carbon dioxide.
¢  2
products are the result of this
rearrangement: food and oxygen.
¢  The
food is in the form of sugars and
starches. These nutrients allow the plant
to grown.
THE OXYGEN IS RELEASED BACK INTO THE
AIR.
¢  This
process is called photosynthesis.
IMPORTANCE OF PHOTOSYNTHESIS
¢ The
process of photosynthesis
can be written as a word
equation:
PHOTOSYNTHESIS IS IMPORTANT TO YOUR
LIFE FOR TWO MAIN REASONS…
¢ One:
It converts the sun’s energy
into chemical energy in plants and
stores it in the form of sugars and
starches. Your body can use this
stored energy when you eat plants,
plant-based products (bread), or
plant-eating animals.
¢ Two:
It provides the oxygen in
the air you breathe.
¢ Do
you remember how much
scientists calculated it would
cost humans to purchase all the
“services” photosynthesis
provides?
PHOTOSYNTHESIS IS THE ONLY
PROCESS
¢ That
allows other living things in an
ecosystem to use the sun’s energy.
How important IS the rainforest??!!
¢ Through photosynthesis, plants
produce the food and oxygen that all
food consumers need to survive.
¢ That’s why scientists call plants and
plant-like things producers.
OXYGEN IS FOR MORE THAN JUST
BREATHING.
¢ Plants
need oxygen too!
¢ Nearly
all living things need oxygen
to release the energy that is stored in
their food.
¢ Cellular
respiration is the process
responsible for this release of energy.
CELLULAR RESPIRATION
¢  Is
a chemical reaction that occurs within the
cells of all living things.
¢  Food
+ Oxygen = Carbon Dioxide, Water &
Energy.
¢  Food
¢  The
is in the form of the sugar glucose.
energy and water are used to carry out life
functions. The carbon dioxide is given off (in
plants) and exhaled during breathing (in
animals).
WORD EQUATION FOR CELLULAR
RESPIRATION.
A VITAL INTERACTION
¢  In
photosynthesis and cellular respiration,
the products of one chemical reaction are
used by the other.
¢  Photosynthesis: plants take in carbon
dioxide and water, and produce food and
oxygen.
¢  Cellular Respiration: plants and
animals use food and oxygen to produce
carbon dioxide and water.
A SPECIAL GROUP OF CONSUMERS
¢  All
living things eventually die L
¢  As
well, consumers generate waste
material from the food they eat.
¢  Our
planet would be littered with dead
bodies and waste material if not for a
special group of consumers.
SCAVENGERS & DECOMPOSERS
SCAVENGERS & DECOMPOSERS
¢  Scavengers
are consumers that don’t usually
kill their own food.
¢  They
feed off of the remains of living things killed
by other consumers.
¢  Crows,
ravens, and housefly larvae (maggots…
yuck!) are examples of scavengers.
¢  Can
you name any more?
DECOMPOSERS
¢  Are
consumers that break down (decompose)
dead plants and animals.
¢  They also break down animal waste materials.
¢  Fungi (such as mushrooms), and the mold you
sometimes see growing on bread, fruits, and
vegetables are decomposers.
¢  So are many kinds of bacteria.
¢  Decomposers’ actions mean that plants always
have a supply of nutrients available to them
(and keep the Earth from being buried in dead
bodies, feces, and urine). They act like a bridge
connecting biotic and abiotic factors in the
ecosystem.
DECOMPOSERS CAN BE HELPFUL OR
HARMFUL.
CHECK & REFLECT
¢ Page
33 #s 1, 2, 3 & 4